An inkjet printer is a printer in which ink from a supply reservoir is transformed into small droplets which are propelled toward a paper document in seriatim. The droplets are exposed to an electrical field to cause them to assume a net charge whereupon deflection plates which are selectively energized by deflection voltage means cause the droplets to be deflected from a normal straight line path toward a paper document so as to form plural series of dots which collectively represent a character, symbol or other graphic patterns, in much the same way as characters are formed in impact printers of the dot matrix type, for example as taught by U.S. Pat. No. 3,703,949 issued Nov. 28, 1972 and assigned to the assignee of the present invention.
Inkjet printers typically utilize either of two basic methods for supplying ink from an ink supply to the inkjet head containing the nozzle or nozzles, depending upon the type of head employed. The first one of the above methods utilizes an ink supply reservoir which is mounted in a stationary position and is coupled to the inkjet head by means of a flexible tube for transporting ink to the head. The second method utilizes an ink supply reservoir which is mounted upon the same carriage as the inkjet head and which is transported with the head during printing, whereby the ink droplets are deflected vertically upward or downward while the head is moved across the paper document, in conventional printer designs.
Both of the above methods are cumbersome and costly and present a number of problems. The method in which a stationary reservoir is connected to the inkjet head through a tube requires an expensive pressure system to force the ink into the head and there is always the danger of breakage in the tube and spillage in the system. In the second method, the major problem is the transportation of the ink supply reservoir which reaches a practical limit as to the amount of ink which can be transported with the carriage, it being quite important to reduce the mass of the moving elements in order to achieve high printing speeds and to avoid the need for large driving means required to move such large masses.